Citrate esters

Abstract

Citrate esters are formed utilizing organic titanates as a catalyst allowing excess alcohol to be removed. Four citrate esters have been found which provide advantageous plasticizing properties to PVC compositions which include superior toxicity test results and superior soapy water extraction test results. The four citrate esters are: acetyltri-n-hexyl citrate, n-butyryltri-n-hexyl citrate, acetyltri-n-(hexyl/octyl/decyl) citrate, and acetyltri-n-(octyl/decyl) citrate. Articles formed from the PVC plasticized mixtures are extremely useful in the medical or health care field as they demonstrate a low order of toxicity.

I claim: 
     
       1. A citrate ester selected from the group consisting of acetyltri-n-hexyl citrate and n-butyryltri-n-hexyl citrate, said ester having an aconitate level of less than 0.20% when the esterification mixture from which said citrate is produced tests about 0.6% maximum acidity calculated as citric acid, said ester having heat stability characteristics, after heating at 150° C. for two hours, of a color not greater than 50-60 APHA and a mild odor at 25° C. 
     
     
       2. A citrate ester selected from the group consisting of acetyltri-n-hexyl citrate and n-butyryltri-n-hexyl citrate, said ester having an aconitate level of not greater than 0.18% when the esterification mixture from which said citrate is produced tests about 0.9% maximum acidity calculated as citric acid, said citrate ester having heat stability characteristics, after heating at 150° C. for two hours, of a color not greater than 50-60 APHA and a mild odor at 25° C. 
     
     
       3. The ester of claim 2 wherein said aconitate level is not greater than 0.15%. 
     
     
       4. The ester of claim 2 wherein said aconitate level is not greater than 0.10%. 
     
     
       5. A citrate ester selected from the group consisting of acetyltri-n-hexyl citrate and n-butyryltri-n-hexyl citrate, said ester having an aconitate level of less than 0.20% when the esterification mixture from which said citrate ester is produced tests in the range from about 0.6% to 0.2% acidity calculated as citric acid, said citrate ester having heat stability characteristics, after heating at 150° C. for two hours, of a color not greater than 50-60 APHA and a mild odor at 25° C. 
     
     
       6. A citrate ester selected from the group consisting of acetyltri-n-hexyl citrate and n-butyryltri-n-hexyl citrate, said ester having an aconitate level of not greater than 0.15% when the esterification mixture from which said citrate ester is produced tests in the range from about 0.9% to 0.45% acidity calculated as citric acid, said citrate ester having heat stability characteristics, after heating at 150° C. for two hours, of a color not greater than 50-60 APHA and a mild odor at 25° C. 
     
     
       7. A citrate ester selected from the group consisting of acetyltri-n-hexyl citrate and n-butyryltri-n-hexyl citrate, said ester having an aconitate level of not greater than 0.10% when the esterification mixture from whch said citrate ester is produced tests in the range from about 0.9% to 0.35% acidity calculated as citric acid, said citrate ester having heat stability characteristics, after heating at 150° C. for two hours, of a color not greater than 50-60 APHA and a mild odor at 25° C. 
     
     
       8. The ester of claim 1 wherein said ester is acetyltri-n-hexyl citrate. 
     
     
       9. The ester of claim 1 wherein said ester is n-butyryltri-n-hexyl citrate. 
     
     
       10. The ester of claim 2 wherein said ester is n-butyryltri-n-hexyl citrate. 
     
     
       11. The ester of claim 2 wherein said ester is acetyltri-n-hexyl citrate. 
     
     
       12. A citrate ester selected from the group consisting of acetyltri-n-hexyl citrate and n-butyryltri-n-hexyl citrate, said ester having an aconitate level of less than 0.20% when the esterification mixture from which said citrate is produced tests about 0.6% maximum acidity calculated as citric acid wherein said ester has a heat stability characteristics, after heating at 150° C. for two hours, of a mild odor at 25° C. 
     
     
       13. A citrate ester selected from the group consisting of acetyltri-n-hexyl citrate and n-butyryltri-n-hexyl citrate, wherein said ester has heat stability characteristics, after heating at 150° C. for two hours, of a color not greater than 50-60 APHA and a mild odor at 25° C. 
     
     
       14. The ester of claim 13 wherein said ester is acetyltri-n-hexyl citrate. 
     
     
       15. The ester of claim 13 wherein said ester is n-butyryltri-n-hexyl citrate. 
     
     
       16. A citrate ester selected from the group consisting of acetyltri-n-hexyl citrate and n-butyryltri-n-hexyl citrate, wherein said ester has a heat stability characteristics, after heating at 150° C. for two hours, of a mild odor at 25° C. 
     
     
       17. The ester of claim 16 wherein said ester is n-butyryltri-n-hexyl citrate. 
     
     
       18. The ester of claim 16 wherein said ester is acetyltri-n-hexyl citrate.